SA58670 NXP Semiconductors, SA58670 Datasheet - Page 18

• Manufacturer Part Number: SA58670
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SA58670_3
Product data sheet
11.5 Efficiency and thermal considerations
11.6 Additional thermal information
The maximum ambient operating temperature depends on the heat transferring ability of
the heat spreader on the PCB layout. In
factor is given as 41.6 mW/K. The device thermal resistance, R
power derating factor. Convert the power derating factor to R
For a maximum allowable junction temperature T
maximum device dissipation of 1.5 W (750 mW per channel) and for 2.1 W per channel
output power, 4
Equation
The maximum ambient temperature is 114 C at maximum power dissipation for 5 V
supply and 4
thermal protection circuitry turns the SA58670 off; this prevents damage to IC. Using
speakers greater than 4
reducing the output load current and increasing amplifier efficiency.
The SA58670 HVQFN20 package incorporates an exposed DAP that is designed to
solder the mount directly to the PCB heat spreader. By the use of thermal vias, the DAP
may be soldered directly to a ground plane or special heat sinking layer designed into the
PCB. The thickness and area of the heat spreader may be maximized to optimize heat
transfer and achieve lowest package thermal resistance.
R
T
th j-a
amb max
=
4:
----------------------------------------- -
derating factor
=
T
j max
load. If the junction temperature of the SA58670 rises above 150 C, the
1
load, 5 V supply, the maximum ambient temperature is calculated using
–
R
Rev. 03 — 11 June 2009
th j-a
further enhances thermal performance and battery lifetime by
=
--------------- -
0.0416
P
1
max
=
=
24 K /W
Table 3 “Limiting
150
2.1 W/channel stereo class-D audio amplifier
–
24 1.5
j
= 150 C and R
values”, the power derating
=
114 C
th(j-a)
th(j-a)
th(j-a)
by
is the reciprocal of the
Equation
SA58670
= 24 K/W and a
© NXP B.V. 2009. All rights reserved.
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